Vietnam is an important producer of aquaculture products, and aquatic products are essential to the Vietnamese diet. However, Vietnam also has very little enforced regulation pertaining to antibiotic usage in domestic aquaculture, which raises concerns for antibiotic resistance in pathogenic bacteria. In this study, analysis was conducted on the presence of antibiotic residues in domestically sold fish and shrimp raised in freshwater farms in Vietnam, and an assessment of farmers’ knowledge of proper antibiotics usage was performed. The results indicated that a quarter of tested aquaculture products were antibiotic screening test positive, and there is a general lack of knowledge about the purpose and proper usage of antibiotics by aquaculture producers. Farmers’ decision-making processes about antimicrobial use are influenced by biased sources of information, such as drug manufacturers and sellers, and by financial incentives.Electronic supplementary materialThe online version of this article (doi:10.1007/s10393-014-1006-z) contains supplementary material, which is available to authorized users.

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Aquaculture systems are highly complex, dynamic and interconnected systems influenced by environmental, biological, cultural, socio-economic and human behavioural factors. Intensification of aquaculture production is likely to drive indiscriminate use of antibiotics to treat or prevent disease and increase productivity, often to compensate for management and husbandry deficiencies. Surveillance or monitoring of antibiotic usage (ABU) and antibiotic resistance (ABR) is often lacking or absent. Consequently, there are knowledge gaps for the risk of ABR emergence and human exposure to ABR in these systems and the wider environment. The aim of this study was to use a systems-thinking approach to map two aquaculture systems in Vietnam – striped catfish and white-leg shrimp – to identify hotspots for emergence and selection of resistance, and human exposure to antibiotics and antibiotic-resistant bacteria. System mapping was conducted by stakeholders at an interdisciplinary workshop in Hanoi, Vietnam during January 2018, and the maps generated were refined until consensus. Thereafter, literature was reviewed to complement and cross-reference information and to validate the final maps. The maps and component interactions with the environment revealed the grow-out phase, where juveniles are cultured to harvest size, to be a key hotspot for emergence of ABR in both systems due to direct and indirect ABU, exposure to water contaminated with antibiotics and antibiotic-resistant bacteria, and duration of this stage. The pathways for human exposure to antibiotics and ABR were characterised as: occupational (on-farm and at different handling points along the value chain), through consumption (bacterial contamination and residues) and by environmental routes. By using systems thinking and mapping by stakeholders to identify hotspots we demonstrate the applicability of an integrated, interdisciplinary approach to characterising ABU in aquaculture. This work provides a foundation to quantify risks at different points, understand interactions between components, and identify stakeholders who can lead and implement change.

Determination and kinetics of enrofloxacin and ciprofloxacin in Tra catfish (Pangasianodon hypophthalmus) and giant freshwater prawn (Macrobrachium rosenbergii) using a liquid chromatography/mass spectrometry method. J. vet. Pharmacol. Therap. 34, 142-152. The fluoroquinolones enrofloxacin (EF) and ciprofloxacin (CF) residues were investigated in the edible tissues of two important Asian aquacultured species such as Tra catfish (Pangasianodon hypophthalmus) and giant freshwater prawn (Macrobrachium rosenbergii) using a sensitive liquid chromatography-electrospray ionization-tandem mass spectrometry method. Fish and prawn were treated with medicated feed with multiple doses of EF, in field conditions. A validation study of the analytical method was realized in terms of linearity, specificity, precision (repeatability and within-laboratory reproducibility), recovery and decision limit (CCα). The time needed before the antibiotic disappears from animal tissues or reach the maximum residue limit (MRL, 100μg/kg) was assessed. The concentration values of EF detected in Tra catfish tissue were between the MRL and 2×MRL concentrations, according to the fish density, 7days following the end of the enrofloxacin treatment (20mg/kg body weight per day, for seven consecutive days). The concentration value of ER in prawn tissue was lower than the MRL and the limit of quantification (LOQ, 14μg/kg) 5 and 7days after the stop of the EF treatment (50mg/kg body weight per day, for five consecutive days), respectively. The mean detected levels of CF was much lower in comparison with that of EF, indicating that only a small part of EF is metabolized into CF (<5%) in both Tra catfish and prawn.

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Growth is an economically important trait for farm animals and can be defined as any change in body size such as body weight or length per time unit (Narinç et al. 2017). This trait is influenced by genetic factors, environmental factors such as feeding condition, and the interaction between them. The knowledge of animal growth is important for the improvement of management and feeding practices in order to maximize the profit of livestock industry (Narinç et al. 2017; Do & Miar 2020). Mathematical models have been successfully characterized growth patterns and visualized the shape of growth over time. Among these models, non-linear models are the most applied models as they allow the interpretation and understanding of growth patterns underlying growth periods (Schnute 1981). Several non-linear models such as the Gompertz (Gompertz 1825), Logistic (Pearl 1977), Bridges (Bridges et al. 1992), and Richards (Richards & Kavanagh 1945) are widely used to describe the growth curve (Kaplan & Gürcan 2018). The growth parameters derived from mathematical models have shown that these parameters are heritable and are responsive to the selection programs (Mignon-Grasteau et al. 2000; Manjula et al. 2018).In Vietnam, chicken is one of the most common farm animals.The species is not only important for the food resources for people but also for the cultures of the country. Vietnam owns about

The aim of this study was to evaluate the effects of diets containing rice distillers’ by‐product (RDP) on growth performance, carcass characteristics, meat quality, and gut microbiota of fattening pigs. Twenty‐four crossbred finishing pigs (Duroc × Landrace × Yorkshire), 56.9 ± 3.1 kg initial body weight, were randomly allocated to three groups. For 56 days, pigs were fed one of three diets including RDP0 (control), RDP15 (15% RDP in DM), and RDP30 (30% RDP in DM). With RDP level in diet, average daily gain and backfat thickness linearly increased (p < 0.05), and drip loss tended to increase (p ≤ 0.08). In addition, 16S ribosomal RNA gene amplicon profiling showed that RDP was associated with modulation of colonic microbiota composition, especially at family and genus levels. Relative abundance of Porphyromonadaceae and Erysipelotrichaceae families in colonic digesta increased with inclusion of RDP, while that of Enterobacteriaceae decreased. The proportion of genera unclassified Erysipelotrichaceae, and Butyrivibrio increased as inclusion of RDP. These results indicate that up to 30% inclusion in diet of finishing pigs, RDP can modulate colonic microbiota composition, and induces an improvement of animal growth and fat deposition.

Abstract:The objectives of this study were to determine the morpho-biometric characteristics of Vietnamese indigenous Ho chicken breed and to evaluate its production, reproduction performance and egg quality. The study was carried out on 20 households raising purebred Ho chicken from September 2013 to April 2015 in Northern Vietnam. Morpho-biometric characterization was based on measurement of 128 adult individuals. The egg production was observed on 66 hens within 20 households. A total of 29 eggs were freshly collected from 8 hens at the 20th laying week for quality analysis. Ho chicken breed is a breed with a large dimension, a large diversity in the colors (black with gold hackle, black copper, wheat, tan and tricolor), a heavy weight (3.78 and 2.64 for adult males and females, respectively), a low egg production (12.73 eggs/clutch) and a relatively low rate of embryo eggs (72.81%). A research to improve the egg production and reproduction should be undertaken to obtain a better performance, economic efficiency while maintaining this genetic heritage and sustaining the biodiversity of the avian breeds in Vietnam.